According to my books the bond order of $ceCO+$ is $3.5$. But shouldn"t it be $2.5$? On googling this, I uncovered the adhering to answer that is on Stack Exchange however its just talks around the bond size.

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I am unable to understand also why it is $3.5$ as I am in course 11.



For a long time it was taught in school and also universities that the HOMO of carbon monoxide is anti-bonding. Without more conmessage it was likewise regularly taught that the bond order in CO is 3, because there are eight electrons in bonding orbitals and two in anti-bonding orbitals. $$ extBond order = frac12( extbonding - extanti-bonding)$$By assuming that the HOMO is anti-bonding (it is not!) and taking ameans one electron, the bond order hregarding increase to 3.5. This is wrong.

When we have a look at the MO diagram, a calculated version have the right to be found here, we know that the HOMO, i.e. 3σ, is a bonding orbital, while the anti-bonding orbital is the 2σ. Upon ionisation, we would indeed remove one bonding electron and therefore the bond order hregarding decrease to 2.5 as you said.However, it is not that straightforward. Strictly speaking the below MO scheme is, as well as MO theory itself, an approximation, and also only one possible configuration. While we carry out not have to usage resonance frameworks via MO theory, we have to take into consideration other configurations (analogous to excited states). So naturally the bond order of CO is not strictly 3. And removing an electron does not mean we are removing it from just one orbital, quite than decreasing the electron thickness. Because of this we cannot accurately predict the bond order through these basic considerations.Experipsychological monitorings and theoretical calculations imply that the bond indeed becomes stronger once removing an electron. See the linked question and also Philipp"s answer within for even more detail. (Don"t look at the other answers, they are as wrong as they might be.)

In short: The bond order of $ceCO$ is not precisely 3 and removing an electron will not boost the bond order to 3.5. In both instances, the oboffered bond order is probably closer to 2.5, while experiments indicate that the bond is stronger in $ceCO+$.

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An orbital with bonding character has actually no node perpendicular to the bond axis; an orbital via anti-bonding character has at leastern one node perpendicular to the bond axis (electron density is zero). Strictly speaking tright here are no non-bonding orbitals.